Inhibition Of EEF-2 Kinase Sensitizes Melanoma Cells To Vemurafenib Therapy And Its Molecular Mechanism

Objective:To study the effect of Eukaryotic elongation factor 2 kinase(eEF-2K)on melanoma cells survival, proliferation and sensitivity to Vemurafenib.Methods: To study the regulatory role of eEF-2K in melanoma cells survival and proliferation, and the regulatory role of eEF-2K in mediating vemurafenib therapy resistance, and provide a novel therapeutic regimen for malignant melanoma.Cell biology, molecular biology and pharmacology methods were used in this study.Results:We demonstrated:1)eEF-2K is over-expressed in BRAF(V600E)melanoma cell lines, and contributes to melanoma cells survival and proliferation, as evidenced bysilence ofeEF-2K or treatment with NH125(a specific inhibitor of eEF-2K) decreases cell growth and proliferation, and increases Annexin V staining. 2)eEF-2K contributes melanoma cells toVemurafenib therapy resistance. Vemurafenibtherapy decreases the level of p-eEF2 in Vemurafenib-Sensitive melanomas, but not in Vemurafenib-Resistant melanomas, and silence of eEF-2Kor treatment with NH125 can increase the cytocidal activity of Vemurafenib in melanoma cells. Furthermore, we demonstrate that sensitization of melanoma cells to Vemurafenibis accompaniedby a down-regulation of the anti-apoptotic protein, Survivin, and that overexpression of survivincan abrogatethe sensitizing effect of inhibiting eEF-2K on Vemurafenib. 3)Combination ofvemurafenib and NH125 inducessynergisticgrowth suppression in melanoma cells, as indicated by COMPUSYN software analysis.Conclusions: eEF-2K plays an important role in regulating melanoma cells survival and proliferation, and anti-apoptosis activation induced by eEF-2K, which is mediated by survivin, is involved in cellular resistance to Vemurafenib. These findings should help further understand the molecular and cellular functions of eEF-2K in cancer, and may provide a potential target for melanoma treatment.